Canada



J. S. PEARCE. PROCESS AND APPARATUS FOR PRODUCING CHARCOAL AND LIKE MATERIALS.

APPLICATION HL'ED MAR. (HI 1919.

Patented Nov. 1, 1921.

Jw/ Z0 ATTORNEY- UNITED STATES PATENT OFFICE.

JOHN STUART PEARCE, OF VANCOUVER, BRITISH COLUMBIA, CANADA.

Specification of Letters Patent.

Patented Nov. 1, 1921.

Application filed March 31, 1919. Serial No. 286,549.

T 0 all whom it may concern:

Be it known that 1, JOHN STUART PEARCE, a citizen of Canada, residing at Vancouver, in the county of New Westminster and Province of British Columbia, Canada, have invented new and useful Improvements in Processes and Apparatus for Producing Charcoal and like Materials, and has for its object the introduction of a more economical and eflicient 'method than those heretofore proposed.

This invention relates particularly to a new method of carrying out the destructive distillation of waste wood, etc., and producing a very high grade of charcoal, etc., at a minimum cost.

The object of this invention is to provide a method that will be simple in its nature, comparatively easy to carry out and less costly to operate than those at present known. With these and other objects in view the invention consists in the novel steps and combination of steps constituting the process, and the new form of apparatus, all as will be more fully hereinafter disclosed and particularly pointed out in the claims.

The drawing shows a vertical cross section through the apparatus.

A is the part of the furnace in which the fuel is consumed, and the hot combustion gases formed. B is the fuel chamber. C is the fuel bed. H is a gas burner situated in a separate'chamber above BL J is a mass of refractory material, such as broken magnesite brick, etc. U is an arched wall at the rear of the fire-box. V is the arch over the fire-box. P are passages or flues connecting the fire-box B with the chamber holding the material J. D is the main flue carrying the hot combustion gases'from C and J. W is the bridge for retaining the refractory material J. O is a by-pass flue for diverting the combustion gases from their course through the charcoal chamber during filling and emptying of the latter. S is honeycombed brick work at the end of the flue D. L is the destructive distillation and charcoal forming chamber. X is a discharge door at the bottom of the chamber L through which the charcoal may be removed. R is a car for transporting the charcoal. M are charging tubes. T are doors leading from the exteriorto the charging tubes. N

is the exhaust flue leading from the charcoal chamber. K is a damper in the flue N. K is a damper in the by-pass fiue O. K 1s a damper in the main flue D. Y are small fiues leading from the charging tubes to the flue N.

It is preferable to operate both the upper and the lower fuel chambers but it is the upper one that gives the oxygen-free combustion products. Of course 1f damper K is closed and the gases from the lower grate pass through P the result is the same with the additional advantage that the volume of the gaseous products of combustion is greatly augmented and superheated if desired.

The remarkable activity or catalytic power of incandescent refractory material is well known and it brings about combustion in cases where the proportion of combustible and non-combustible gases is such that they would not ordinarily combine. Although combustible gases and air reacting in presence of this material give out exactly the same amount of heat that they would under any other circumstances, yet the heat is conserved in a limited area and is not dissipated as would otherwise be the case. In addition the combustion is hastened and rendered more complete.

The fuel selected, such as coke, anthracite coal, charcoal, etc., must give off little or no combustible gases while burning, as would be the case were soft coal employed. Other wise there would be a deposition of carbon, etc. that might choke up the fines. It would also deposit upon and more or less change the nature of the charcoal resulting from the wood treatment. Many of the combustible volatile products from soft coal are much less volatile than those escaping during the destructive distillation of wood. Qonsequently these would deposit upon the charcoal anddecrease its value for metallurgical or other purposes. It might mean that sulfur and like objectionable compounds would be thus introduced into the charcoal and thus add to it elements whose absence is its greatest value.

There is an additional objection to the employment of softcoal. Although in this instance the furnace alone is shown and claimed, yet there is another and equally important part of the entire process. That is the recovery and the separation of the wood distillation products, which are of great commercial value. The following shows their relative nature and proportions.

Percent. 1. Noncondensable gases 203O 2. Aqueous distillate, (pyroligneous acid) 3050 3. Turpentine, wood oils and wood tar 5-20 l. Charcoal 20-4l5 At 150 C. the decomposition of the wood commences and is complete at 430 C.

Thereis an absolute difference between the chemical products resulting from a wood and a soft coal destructive distillation. If they were intermingled as would be the case if soft coal were employed in producing the hot combustion gases, the distillation product would be an almost valueless mixture of unknown and uncertain composition.

The fuel, preferably coke or charcoal, is charged into the firebox B through the door 1*. It rests upon a grate set at an angle of perhaps 45 degrees in front, and through this the cold air entering at E passes horizontally into and through the coal and passes into the flue at the rear. When oxygen-free combustion gases are employed the damper K is closed and all the gases pass through the refractory material J. U is the back wall of the fire-box, and has an arch in the center of the lower portion so that the solid fuel may flow and find its own boundary, through which the heated prodnets of combustion may escape. By closing the damper K the direction of the combustion gases is entirely changed, and they'move upward through the fines P and are heated by the incandescent mass J. Below the incandescent material J is situated the burner of any type partially shown at H to raise it to a sufficient temperature to reduce catalytic action.

The size of the burner employed is dependent entirely upon the amount of refractory material. It may be of any type, but must be of such a size that it can alone maintain the refractory material in a state of incandenscence, although normally only a part of this heat is required of the burner, the remainder being furnished by the combustion of the fuel in the lower hearth.

The destructive distillation of the waste wood takes place in the chamber L. It is introduced through the doors or covers T into the charging tubes M which also act as preheaters. Being surrounded by an air space the hot gases surround them, and the fines Y also allow a portion of the heated gases to flow through the waste wood in M and into the flue N.

From the chamber L the gases are drawn into the flue N and from there into the condensers, not shown in this application, for collecting the DlOClUCtS of distillation.

A very important feature of this device though not shown as it may be of any standard type, is the apparatus for producing a suction. Apparatus of this nature, such as a fan, etc., is so well known and of such common occurrence that it has not been shown in the drawing. Its function is to cause a current of air to enter at E and the gaseous products to be removed at N. The exhaustion apparatus is connected with the exhaust pipe N, but is not shown in the drawing.

The three dampers K K K are intended to regulate the movements of the gaseous currents. If the chamber L is to be cut oil as in discharging the charcoal and filling with wood waste K and K are closed.

Although it is not shown in the drawing and is not claimed in this application, the gas employed in the burner H is one of wood destructive distillation. It is always advisable to scrub the gas and remove the carbon dioxid before attempting to burn it, but in this case its complete removal is not so essential as the incandescent refractory material aids the combustion.

The present application is intended to show and does show the particular advantages resulting from the direct action of the hot products of combustion upon the wood. In this way the yield is greater than could possibly result from any system of indirect heating, and the gases that are introduced are of material aid in carrying oif the products of distillation.

Although in this application I have placed particular stress upon the treatment of wood, I do not wish to be limited in this respect as both my process and apparatus may be employed in the treatment of coal, lignite or shale.

A particular feature of this invention is the partial or complete superheating of the products of combustion and the complete removal of free oxygen which makes it possible to speed up the reaction or regulate it in any way desired.

Among the various advantages that my process possesses over those already known, I have discovered after exhaustive research that I am enabled to regulate very accurately the heat to which the wood is subjected in various stages of the process. This makes it possible for me to meet the requirements in relation to three factors of great importance, 2'. 6., 1st, the quality of the byproducts, 2nd., the quality of the charcoal, 3rd, the speed of the reaction.

To obtain the best results it is necessary to expel the adhering moisture, as well as that formed by the chemical decomposition just prior to the beginning of the exothermic reaction, as quickly as possible. By means of my incandescent refractory material and my separate solid fuel and gas heatin de vice I can accomplish this with ease. ater when the exothermic reaction is going on I control the heat in a way that produces a very high yield of volatile products that are of Very considerable value. After this stage is passed the temperature is raised rapidly and the charcoal finished at a much higher heat than would be possible in ordinary processes. This has the effect of producing a remarkably high grade of charcoal, and one that may advantageously replace coal and coke as powdered fuel for metallurgical purposes.

Referring now to the best mode of operation, I may 'say that at flrst the solid fuel chamber is made to supply the bulk of the heat, and the gas is simply used to keep the refractory material hot. At this stage at least two thirds of the heat is supplied by the solid fuel. In the second or intermediate stage the heat may be supplied by either the solid or gaseous fuel. In the later stage two thirds of the heat is supplied by the gas. It is this stage that is of particular importance in determining the value of the charcoal, and this particular improvement constitutes a very important feature of my invention. By quickly raising the temperature in the last stage and finishing the charcoal at a very high temperature obtain a very superior product, and one eminently fitted for metallurgical work, and especially adapted for burning as powdered fuel. My invention thus comprises not only a new method of producing charcoal but in reality a new type or quality of charcoal.

It is obvious that those skilled in the art may vary the form of apparatus as well as the details of the process without in any way departing from the spirit of the invention. Therefore I do not wish to be limited to the above disclosures except as may be required by the claims.

1' claim V 1. A method of destructive distillation which comprises bringing gaseous products of combustion into intimate contact with a mass of independently heated refractory material, designed to act as a catalyst, and then through a mass of wood waste; substantially as described.

2. A method of destructive distillation which comprises passing the products of combustion of solid fuel through a mass of refractory material in contact with which heated gaseous fuel is being burned, and leading the combined products of combustion through a mass of wood; substantially as described.

3. A method of destructive distillation which comprises passing products of combustion heated to a temperature slightly below that at which they pass from the fuel, and mixed with other products of combustion superheated in passing through incandescent refractory material, in contact with a mass of wood, and removing the volatile products of decomposition associated with the originally introduced products of combustion; substantially as described.

4. In an apparatus for destructive distillation, a combustion chamber divided into two parts, one part adapted to consume solid fuel and the other part adapted to consume gaseous fuel, a mass of refractory material in the gaseous fuel section, a flue leading from the fuel chamber to the charcoal forming chamber, a charcoal forming chamber with a discharge flue adapted to remove the gases, and a discharge door adapted to remove the charcoal substantially as described.

5. In an apparatus for destructive distillation, a combustion chamber divided into two parts, the upper one being adapted to consume gaseous fuel, and the lower one be ing adapted to consume solid fuel, a flue connecting the lower and the upper sections of the fuel chamber, a mass of refractory material in the upper section of the fuel chamber, a common flue leading from the two sections of the fuel chamber to the charcoal forming chamber, a charcoal forming chamber with a discharge flue adapted to remove the gases, and a discharge door adapted to remove the finished charcoal; substantially as described.

6. In an apparatus for destructive distillation, a combustion chamber divided into two parts, the upper one being adapted to consume gaseous fuel, and the lower one adapted to consume solid fuel, a flue connecting the lower and the upper sections of the fuel chamber, a mass of refractory material in the upper section of the fuel chamher, a common flue leading from the two sections of the fuel chamber with a damper adapted to shut off the lower section of the fuel chamber, the said flue leading into the charcoal forming chamber, a charcoal forming chamber, charging chambers in the up per portion of the charcoal forming chamher and surrounding the flue adapted to carry off the escaping gases, lattice work in the lower portion of the charcoal forming chamber and adapted to support the mass of wood, an outlet in the bottom of the charcoal forming chamber adapted to discharge the finished charcoal; substantially as described.

JOHN STUART PEARCE. 

